Test means for aircraft gyrocontrolled attitude indicator



July 15, 1952 J, m w 2,603,696

TEST MEANS FOR AIRCRAFT GHQ-CONTROLLED ATTITUDE INDICATOR FiledOct. 4, 1951 3 Sheets-Sheet l MON v hmuh KOFOK 0x6 21 MN kNN WNW :3

4T TORNEYS I N VEN TOR.

July 15, 1952 McEwAN 2,603,696

TEST MEANS FOR AIRCRAFT GYRO-CONTROLLED ATTITUDE INDICATOR Filed Oct. 4, 1951 I5 Sheets-Sheet 2 FIG. 3

IN V EN TOR.

ARCH/B D A? IZM A r ram: rs

July 15, 1952 J, McEwAN 2,603,696

TEST MEANS FOR AIRCRAFT GYRO-CONTROLLED ATTITUDE INDICATOR Filed Oct. 4, 1951 3 Sheets-Sheet 3 A T TORNE Y5 Patented July 15, 1952 TEST MEANS FOR AIRCRAFT GYRO- CONTROLLED ATTITUDE INDICATOR Archibald John McEwan, United States Navy Application October 4, 1951, Serial No. 249,793

12 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 O. (3.757)

This invention relates to testing apparatus, and more particularly to testing apparatus suitable for use with the aircraft gyro-controlled attitude indicator described and claimed in my co-pending application Serial No. 166,951, filed 8 June 1950.

One of the objects of the invention is to provide new and improved testing apparatus.

Another object is to provide new and improved testing apparatus for quickly and conveniently calibrating an attitude indicator.

Other objects and advantages will become apparent after a consideration of the following specification when taken in connection with the accompanying drawings, in which:

Fig. 1 is a front elevational view of the testing apparatus;

Fig. 2 is an electrical circuit diagram of the testing apparatus of Fig. 1; 1

Fig. 3 is an electrical circuit diagram of the attitude indicator showing the electrical connector terminals for connecting the test apparatus;

Fig. 4 is an electrical circuit diagram of suitable gyroscope apparatus and power supplies;

Fig. 5 is an electrical circuit diagram of the pilots indicator; and f i Fig. 6 is an electrical circuit diagram or the wing indicator lights.

Referring now to the drawings, in which like reference characters are used throughout to designate like parts, and more particularly to Figs. 3, 4, 5, and 6 thereof, the circuits and operation of the attitude indicator apparatus itself will first be described to form a basis for a more proper understanding of the operation of the testing apparatus. There is shown at I0, Fig. 4, a power supply ofany convenient design for providing a three phase alternating current voltage, of, for example. 26 v., 400 cycles/sec. The power supply has one terminal connected to ground 46, and three terminals thereof connected to the Y-connected coils H, l2, and I3 ofa suitable gyroscope motor. A" tapped portion of coil I3 is connected by way of leads [4 and I5 to energize coil I9, which is inductively coupled to coil iii of a pitch autosyn device and which includes coils or windings IS and I1 Y-connected thereto. The outer terminals of'coils or winding IS, IT, and is are respectively connected'to the terminals AA, BB, and CC of multiple terminal plug I9l,

which is adapted to fit with jack I92, Fig. 3, while the apparatus is being used for attitude indication. Plug [BI is removed, and replaced by another plug, when the apparatus is to be tested, as will be hereinafter morefully apparent;

One phase of the 26 v. A. C. voltage from supply I0 is applied to plug terminal FF, as shown.

Another power supply 26 is also shown, for providing a suitable D. C. source of, for example, 28 volts to ground. The output terminal of supply is directly connected to terminal GG of plug lili, and is also connected by way of resistor 63 to terminal DD of plug I9I. Any suitable switch, not shown, may be insertedin the lead to GG to permit on-ofi control of the lights without deenergizing the amplifier.

Terminal EE of plug IBI is connected to ground, as shown. Terminal HH is connected to an altitude device I12 of any suitable design and which is constructed and arranged to generate an output signal whenthe altitude of the aircraft falls below a predetermined value.

Terminals II and LL of plug I3! are connected together, and terminals J J and KK are connected together, as shown.

Particular reference is made now to Fig. 3. Terminal A of aforementioned jack I92 is connected by way of lead 29 to the outer terminal of coil or winding 24 of a zero set autosyn generally designated 240, which includes Y-connected thereto coils or windings 22 and 23. The outer terminal of Winding 22 is connected by way of lead 2| to terminal B of jack I92, and the outer terminal of coil 23 is connected by way of lea 20 to terminal C of jack I92. Lead 20 is also connected by way of variable resistor I 98 to terminal P of an additional jack I94. for purposes to be hereinafter explained. The zero set of autosyn 24B is provided by adjusting the relative positions of coils 22, 23, and 24 with respect to a coil or winding 25, any suitable means, not shown, being provided for this purpose. Coil 'ifiapplies its output across the series connected resistor 40 and potentiometer 3D. The arm of potentiometer 30 is connected to a suitable tap or inductor 21, which has one end thereof connected to ground 46, and the other end thereof connected by way of resistor 3I-to the control grid 36 of the first triode section of a dual triode tube 38. The cathode 31 of the. first tube section is connected by way of resistor 33' to ground 46, the resistor 33 having capacitor 32 connected in shunt therewith. The anode 35 of the first tube section is connected to one terminal of the primary 44 of a transformer having center-tapped secondary 45, the other terminal of the primary 44 being connected by way of lead 39 to terminals I andJ of jack I92. Lead 39 is connected by way of resistor 31 to ground it, resistor 31 having capacitor 35 connected in shunt 3 therewith. Lead 39 is also connected by way of resistor 36 to the cathode 43 of the second triode section. Cathode 43 is connected to ground 46 by way of capacitor 34.

The center tap of the aforementioned secondary 45 is connected by way of resistor 49 to ground, resistor 49 having capacitor 48 connected in shunt therewith. The aforementioned center tap is also connected by way of resistor 41, lead 80, and fuse 8| to terminal F of jack I92. Lead 80 i connected as shown to anode 4| and grid 42 of the second tube section of dual triode 38.

The ends of the aforementioned center-tapped secondary 45 are connected to the anodes 5! and 53 of the diode sections of a dual diode tube 50. Cathode 52 is connected by way of series connected resistors 55 and 58 to the control grid 69 of a triode having anode 68 and cathode I0. Aforementioned cathode 54 is connected by way of series connected resistors 58 and 59 to the control grid 12 of a triode having anode H and cathode 13. The two last named triodes preferably have similar characteristics.

The junction between resistors 55 and 56 is connected by way of capacitor 8| to ground 45, and the junction between resistors 58 and 59 is connected by way ofcapacitor 63 to ground 45. Grid 09 i connected by way of resistor 51 to ground, resistor 51 having'capacitor 62 in shunt therewith, and grid 12 is connected by way of resistor 60 to ground, resistor 60 having capacitor 64 connected in shunt therewith.

The aforementioned cathodes and 13 are connected together and by way of resistor 86 to ground. Resistor 86 has capacitor 81 connected in shunt therewith. V

The aforementioned anode 68 i connected to one terminal of one winding 15 of a first differential relay, the other terminal of winding 15 being connected by way of lead 91 to one terminal of the first winding 93 of a second differential relay. The other terminal of winding 93 is connected by way of lead 99 to terminal K of aforementioned jack I92.

Anode H is connected to one terminal of the second winding 16 of the aforementioned first diiferential relay. The other terminal of winding 16 is connected by way of lead 98 to one terminal of the second winding 94 of the second aforementioned differential relay, the other terminal of winding 94 being connected by way of lead I00 to terminal L of jack I92. Leads 91 and 98 are connected together by way of the series connected resistors 84 and 85, resistor85 preferably being variable.

The movable armature 11 of the first mentioned differential relay is connected to ground 46. One contact 18 of the differential relay is connected by way of lead I I9 to one terminal of the winding I 22 of a multiple relay having armatures I24 and I21. The other terminal of winding I22 is connected by way of lead I06 to post G of jack I92. The other contact 19 of the first differential relay is connected by way of lead I20 to one terminal of thewinding I3I of a second multipole relay having armatures I36 and I33. The other terminal of the winding I3I is connected to lead I06. Armatures I24 and I21 are adapted to be moved upward, Fig. 8, when coil I22 is energized. Armature I24 has associated therewith contacts I23 and I25, and armature I21 has associated therewith contacts I26 and I28. s

Armatures I 36 and I33 are adapted to be moved down, Fig. 3, when winding I3I is energized. Armature I36 has associated therewith contacts I35 and I31, and armature I33 has associated therewith contacts I32 and I34.

Contact I31 is connected by way of lead I01 to terminal S of jack I94,-and terminal W of jack I96. Contact l35-is connected-by way of lead I08 to terminal T of jack I94 and terminal X of jack I96. Armature I36 is connected to contact I25. Contact I 34 is connected to contact I26 and by way of lead I to contact I54 of a multipole relay generally designated I50, having winding I5 I, and having in addition to the aforementioned contact I54, contact I52, armature I53, contact I55, armature I56, and contact I51. Coil I5 Iis adapted to be energized by the altitude signal from altitude device I12.

Aforementioned armature I33 is connected to contact I28. Contact I32 is connected by way of lead I44 to armature I56. Armature I21 is connected by way of lead I43 and variable resistor I65 to a blinker circuit comprising capacitor I63 and coil I62 connected in parallel therewith. Coil I62 has one end thereof connected .to the aforementioned resistor I85, and the other end thereof connected to armature I and by Way of lead I4I to armature I24. Contactl23 is connected by way of lead I09 to terminal U of jack I94 and terminal Yof jack I96. Contact I6I of the aforementioned blinker circuit is connected to lead I06.

Lead I 43 is connected'by way of resistor I64 and lead I49 to contact 92 and 9| of the aforementioned second differential relay, contacts 92 and 9| having associated therewith armature 99 which is connected to ground.

Contact I51 of the aforementioned altitude signal relay I50 is connected to ground 46, while contacts I52 and I55 are open.

Terminal E of jack I92 is connected to ground, while terminal D is connected by way of the series parallel connected tube filaments to ground.

Terminal Q of jack I94, and terminal Z of jack I96, are both connected to ground.

Particular reference is made now to Fig. 5 in which is shown the pilots indicator, the plug I93 being adapted to cooperate with jack I 94. Three signal lamps I16, I11, and I18 each have one terminal thereof connected to terminals SS, TT, and UU respectively, and all have the other terminal thereof connected by way of lead I19 to terminal QQ, and also to the blade I83 of a single pole double throw switch generally designated I80. Terminal I8I of the switch I is connected to terminals RR, while terminal I82 of the switch I 80 is connected to terminals PP.

In Fig. 6 is shown the wing lamp circuit for the wing lamp generally designated I85, and having three lamps of different colors, green, amber, and red, connected by leads to terminals WW, )QC, YY, and Z2.

In the operation of the above-described apparatus, assume that plug I 9| is fitted with jack I92, plug I93 with jack I94, and plug I95 with jack I96, thereby forming a complete electrical circuit.

The output of the pitch gyro is fed into the zero set autosyn. These may be any conventional design, it being understood that the electrical take-off is along the pitch axis, and that means, not shown, is provided for adjusting the pitch angle which it is desired to use for reference. The output of the zero set autosyn is coupled to the grid 36 of the triode voltage amplifier. The output of this amplifier is transformer coupled by way of the transformer including primary 44 and center-tapped secondary 45 to the dual triode Asaforedescribed, one phase of the three phase A.-C. supply voltage is supplied to lead 80, and an A.-C. voltage drop is developed across resistor 49, which is applied to the center tap of secondary 45. Accordingly,a.phase sensitive arrangement is provided, so that the diode sections of tube 50 are selectively rendered relatively more conducting depending upon the phase relation between the voltage on primary 45 and that on resistor 49. The outputs of the diodes become unbalanced depending upon whether the pitch angle of the aircraft changes above or below the desired values, and the rectified outputs are substantially proportional to the amount of deviation.

It will be understood that terminals are suitably chosen so that, when the aircraft noses down, the current in winding I5 exceeds that in winding I6, and relay I22 is energized while I3I remains deenergized. These rectified outputs are amplified by the triode sections respectively of tube 5|, and applied to the windings I5 and'IB respectively of a first differential relay, and to the windings 93 and 94 respectively of a second differential relay, rectified D. C. plate voltage for both anodes 68 and II being obtained from the cathode 43 of tube 38 by way of leads 39, 99, and I00.

The first micropositioner or polarized relay selectively actuates relays I22 and relay I3I which in turn, by way of leads I01, I08, and I09, result in the energization of the proper bulbs in the approach light indicator and pilots indicator,the amber lamp burning while the aircraft is in the correct approach attitude and the armature" of the first differential relay is in neutral position, a nose-up attitude causing the green lamp to burn, and a nose-down attitude causing the red lamp to burn.

When the differential current attains a predetermined value, the second differential relay is energized to complete the circuit between lead I49 and ground 46, thereby placing the blinker circuit (consisting of the winding I62 of. relay I59, the capacitor I63, resistor I64 which may have a value of 820 ohms, andthe potentiometer I65) in operation. The operation of this relay I59 periodically interrupts the 24 or 28 volt supply to the various approach lights, depending upon the instant positions of the contacts of the other relays, with the result that when the noseup and nose-down attitudes approach an extreme condition the respective lamps begin tov blink at a relatively slow rate.

Assume now by way of description that the aircraft drops below a predetermined altitude, and that the altitude device I12 applies a signal to relay I50, energizing the relay. This relay, while energized, alters the aforedescribed blinker circuit through armature I56, contact I32 of relay I3I, armature I33, contact I29 of relay I22, and armature I21. The result of this operation causes the amber light to blink (if it is illuminated) at a fast rate. Similarly, the red or green lamps occult at a fast rate, corresponding to'the fast rate of the amber lamp. 9 V e I Accordingly, it is seen th'atapparatus is provided in which, for normal landing in which the aircraft has the proper attitude and altitude, the

amber light is illuminated. If the altitude remains as desired, but the plane noses-up, the amber light will go out and the green lightwill come on; if the plane noses-down from the' nor- 223, and 224.

mal attitude, the amber light goes out and the red light I5! comes on. If the deviations become excessive, these lights begin to blink at a slow rate. If the altitude falls below a safe value, the amber lamp will blink at a fast rate even when the attitude is correct; if the attitude becomes such that the nose-up or nose-down is excessive, the lamps will flicker at a fast rate if the altitude falls too low.

Particular reference is made now to Figs. 1 and 2, in which a front panel view and an electrical circuit diagram respectively of the test apparatus are shown. The test set may include a housing 203 having a panel 204 mounted thereon and held in place as by screws 205. Panel 204 has mounted thereon three lamps 2I3, 2I4, and 2I5 which are respectively green, amber, and red, and which, when illuminated, indicate a test condition simulating nose-up, on, and nose-down respectively. Mounted directly below the aforementioned lamp is a test switch 206 which is provided for purposes to be subsequently apparent. On either side of switch 206 are mounted a pair of milliameters 2 I I and 2I2 preferably having similar full scale values, and held in place by screws 2I6 and 2II respectively.

A voltmeterhaving a suitable full scale value of, for example, 30 volts, is provided, and held in place as by screws 2I9.

A cable 200, which it isunderstood contains all the leads to the two plugs I91 and I98, Fig. 2, enters the test unit through gromet 220. A support 202, held in place as by screws 20I, provides a mounting for jack or socket I99. A knob 22! controls the position of the arm of potentiometer 228, Fig. 2. Knob 235 controls the setting of the triple pole double throw switch gen erally designated 230, Fig.2.

The dial 225, and its acoomp'anying scale 22%, Fig. 1, controls the degree of coupling between coils or windings 22I and 222, Fig. 2. v

In using the test set, plug I9 I, Fig. 4, is removed from socket I92, Fig. 3, and placed in socket I99, Fig. 2. Plug I93 is removed from socket I94. Plugs I91 and I98 are then placed in sockets I92 and I94 respectively, and the test apparatus is ready for use.

The test switch I of Fig. 5 and 305 of Fig. 2, when operated, place resistor I90, Fig. 3, across two legs of the autosyn input. This electrically unbalances the three coil stator a predetermined amount depending upon the instant setting of variable resistor I90. Thus by using the caged position of the gyro as a reference, it is a simple matter to unbalance a sufficient amount to cause the amber lamp tolight in the caged gyro position. This automatically measures the angle between the caged gyroposition and the correct flight attitude of the aircraft.

In using the test apparatus of Figs. 1 and 2, with the test set inserted and the selector switch 230 in its ,aircraft gyro? setting as positioned by knob 235, the indicating apparatus operates in its normal manner, with the exception that the plate current meters 2 and 2I2 of the test set are connected in series with the plates or anodes II and 68 respectively of dual triode tube 5i, Fig. 3. Switching-the selector switch 230 to the test setting disconnects the aircraft gyro and inserts the output of selsyn generally designated 2! 0, Fig. 2, and having windings 222, By exciting the rotor 22! of the selsyn 2I0 with a suitable voltage, as read on voltmeter 2 I8, the output of the selsyn 2 I0 preferably bears a fixed relation to that of the aircraft gyro in sucha manner that a one-degree rotation of theselsyn dial 225jis equivalent to one degree variation inpitch of the gyro. It thus becomes a simple matter, toiset'the correct attitude indications for the particular aircraft under consideration. Knowing the an les of attack of the horizontal reference line of the aircraft at approach power of 10%, and above stall speed, the attitude indicatorcan be calibrated as follows; for example, with reference attitude. established at 10% speed: a

1. Set indicator dial 225 .of selsyn 210 at correct angle ofattack for 10% above the stall speed condition. j

2. Adjust zero set control on autosyn 240 for an amber light v(balanced plate current meter readings).

3. Adjust sensitivity control 30 until amber lamp is two degrees wide, that is, plus orminus one degree from correct approach path.

4. Adjust deviation control 85 until the red and green lamps blink at 5% and 15% above stall speed points respectively.

5. Check operationof altimeter switch.

6. Cage gyro (this excites the red'lamp) and with test switch pressed, adjust calibrate control until amber lamp is excited.

7. Release test button and uncage gyro.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described The inventiondescribed herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. l

I claim:

1. Test apparatus of the character disclosed for use in conjunction with indicating apparatus on aircraft for indicating to an operator a plurality of aircraft flight conditions including variations in the attitude of the aircraft, wherein the indicating apparatus includes adjustable gyroscope means for obtaining a signal output having signal characteristics corresponding to and determined by the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, andalso having signal characteristics corresponding to and determined by the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and also having signal characteristics corresponding to and determined by the amount of said deviation, a plurality of indicating lamps, a source of potential for said lamps, relay means having contacts, circuit means interconnecting the contacts of said relay means, said source of potential, and said lamps, said relay means having said signal output applied thereto for controlling the application of said potential to said lamps, said relay means being constructed and arranged to utilize said signalcharacteristics to selectively energize said lamps in predetermined manners inv accordance with variations in said pitch angle, in combination, an additional source of potential, and adjustable signal generating means energized from said additional source of potential and detachably connected to said indicating apparatus for creating a signal simulating the signal output of the gyroscope means under predetermined attitude conditions and above stall pitch angle deviations of the aircraft, the relay means of said indicating apparat'u sbeing additionally characterized as including at least two variable circuit elements to permit calibration of the indicating apparatus in accordance with, the simulating signal. j,

2.;Testing apparatus for use with aircraft attitude indicating apparatus inwhich means is employed for obtaining a signal-having a polarity corresponding to the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and having. a magnitude proportional to the amount of said deviation, a plurality of indicating lamps, a source of potential for said lamps, and circuit means including relay means having said signal applied thereto for controlling the application of said potential to said lamps, in combination, an additional source of potential, and adjustable signal generating means energized from said additional source of potential and. detachably connected to said indicating apparatus for creating a signal simulating the signal of the indicating apparatus under preselectedattitude conditions and pitch angle deviations of the aircraft, the circuit means of said indicating apparatus being additionally characterized as including. at least two variable circuit elements to permit calibration of the indicating apparatus in accordance withthe simulating signal.

3. In apparatus of the character disclosedfor use on aircraft, in combination, yroscope means mounted on the aircraft for obtaining a signal having a polarity corresponding to the directionof deviation of the instant, pitch angle of,,the aircraft from a-preselected pitch angle, and having a magnitude proportional. toithe amount of said deviation, pitch indicating apparatusincluding a plurality of lamps and'fde'tachably connected to said gyroscope means, said indicating apparatus while connected to the gyroscope means being constructed and arranged toutilize said signal to, energize the. lamps selectively in accordance with the amount and direction of deviation of the aircraft fromsaid preselected pitch angle, and signal simulating means adapted to.

be detachably connected to the-indicating apparatus, said indicating apparatus including a plurality of variable circuit elements for calibrating the indicating apparatus while thesignal simulating means is connected thereto.

4. In. apparatus of the character disclosed for use on aircraft, in combination, gyroscope means mounted on the aircraft for obtaining a signal having a polarity corresponding to the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and having a magnitude proportional to the amount of said deviation, said gyroscope means including a source of A. C. potential, pitch indicating apparatus including a plurality of lamps and detachably connected tosaid-gyroscope means, said indicating apparatus being so constructed and arranged that, while connected to the gyroscope means, said signal-is utilized toenergize the lamps selectively in-accordance with the amount and direction of deviation of the aircraft'from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected'between the-gyroscope means and the indicating apparatus, said signal simulating means including a variable-signal source energized from said source-of A. C. potential, said indicating apparatus including [a plurality of variable'circuit elements for calibrating the ine capee dicating apparatus'while' the signal simulating means is connected thereto.

H 5. In apparatus of the character disclosed for use on aircraft, in combination, gyroscope means mounted on the aircraft for obtaining a signal having apolarity corresponding to the direction "of deviation of the instant pitch'angle of the aircraft from a preselected pitch angle, and having a magnitude proportional to the amount of said deviation, said gyroscope means including a source of A. C. potential, pitch indicating appara tus including a plurality of lamps and detach ably connected to said gyroscope means, said indicating apparatusfbeingso constructed and arranged that, while connected to the gyroscope means, said signal is utilized to energize the lamps selectively in accordancewith'the amount and direction of deviation of the aircraft from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected between the gyroscope means and the means being energized from said source of A. C.

potential and including a selsyn device having a variable coupling rati'o'to provide a variable signal source, saidindicating apparatus including a plurality of, variable circuit-elements for calibrating the indicating apparatus while the signal simulating meansis connected thereto.

' 6. In apparatus of the character disclosed for use on aircraft, in combination, gyroscope means mounted on the aircraft for obtaining a gyro-- scope signal having a polarity corresponding to the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and having a magnitudeproportional to the amount of. said deviation, said gyroscope means including a source of A. C; potential, pitch indicating apparatus, including a plurality of lamps and detachably connected to said gyroscope means, said indicating apparatus being so constructed and arranged that, while connected to the gyroscope means, said gyroscope signal is utilized to energize the lamps selectively in accordance with the amount and direction of deviation of the aircraft from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected between the gyroscope means and the indicating apparatus, said signal simulating means being energized from said source of A. C. potential and including a selsyn device having ayariable coupling ratio to provide a variable calibrating signal, said signal simulating means including switching mean for selectively switching said calibrating signal and gyroscope signal into said indicating apparatus, said indicating apparatus including aplurality of variable circuit elements for calibrating the indicating apparatus while the signal simulating means is connected thereto.

7. Apparatus according. to claim 6 wherein said signal simulating means includes a plurality of additional lamps corresponding respectively to the plurality of lamps in said indicating apparatus said additional plurality of lamps being energized simultaneously with the other lamps respectively and providing a convenient indication for an operator calibrating the instrument.

8. In apparatus of the character disclosed for use on aircraft, in combination, gyroscope means including an adjustable zero set autosyn mounted on the aircraft for obtaining a gyroscope signal having a polarity corresponding to the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and

having a magnitude'proportional to the amount of said deviation, said gyroscope means including a source of A. 0. potential and a source of D. C. potentiaL pitch indicating apparatus including relay means and a plurality of lamps and detachably connected to said gyroscope means, said indicating apparatus being so constructed and arranged that, while connected to the gyroscope means, said gyroscope signal is utilized to control the relay means and selectively connect said lamps to said D. C. source, in accordance with the amount and direction of deviation of the aircraft from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected between the gyroscope means and the indicating apparatus, said signal simulating means being energized from said source of A. C. potential and including a selsyn device having a variable coupling ratio to provide a variable calibrating signal, said signal simulating means including switching means for selectively switching said calibrating signal and gyroscope signal into said indicating apparatus, said indicating apparatus including a plurality of variable circuit elements for calibrating the indicating apparatus while the signal simulating means is connected thereto.

9 In apparatus of the character disclosed for use on aircraft, in combination, gyroscope means including an adjustable zero set autosyn mounted on the aircraft for obtaining a gyroscope signal having a polarity correspondingto the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and having a magnitude proportional to the amount of said deviation, said gyroscope means including a source of A. C. potential and a source of D. C. potential, pitch indicating apparatus including relay means and a plurality of lamps and detachably connected to said gyroscope means, said indicating apparatus being so constructed and arranged that, while connected to the gyroscope means,- said gyroscope signal is utilized to control the relaymeans and selectively connect said lamps to said D. C. source, in accordance with the amount and direction of deviation of the aircraft from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected between the gyroscope meansiand the indicating apparatus, said signal simulating means being energized from said source of A. C. potential andincluding a selsyn device having a variable coupling ratio to provide a variable calibrating. signal; said signal simulating means including switching means for selectively switching saidcalibrating signal and gyroscope signal into said indicating apparatus, said indicating apparatus including a plurality of variable circuit elements for calibrating the indicating apparatus while the signal simulating means is connected thereto, said signal simulating means also including a plurality of additionallamps corresponding respectively to the plurality of lampsin said indicating apparatus, said additional plurality of lamps being energized simultaneously with the other lamps respectively and providing a convenient indication for an operator calibrating the instrument.

10. In apparatus of the character disclosed for use in aircraft, in combination, gyroscope means including an adjustable zero set autosyn mounted on the aircraft for obtaining. a gyroscope signal having a polarity corresponding to the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and having a magnitude-proportional to the amount of said deviation, said gyroscope means including a source of A. C. potential and a source of D. C. potential, pitch indicating apparatus including relay means and three lamps of different colors and detachably connected to said gyroscope means, said indicating apparatus being so constructed and arranged that, while connected to the gyroscope means, said gyroscope signal is utilized to controlthe relay means and selectively connect said lamps to said D. C. source, in accordance with the amount and direction of deviation-of the aircraft from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected between the gyroscope means and the indicating apparatus, said signal simulating means being energized from said source of A. C. potential and including a selsyn device having a variable coupling ratio to provide a variable calibrating signal, said signal simulating means including switching means for selectively switching said calibrating signal and gyroscope signal into said indicating apparatus, said indicating apparatus including a plurality of variable circuit elements for calibrating the indicating apparatus while the signal simulating means is connected thereto, said signal simulating means also including three additional lamps of difierent colors corresponding respec- 1 tively to the colors of the lamps in said indicating apparatus, said additional three lamps being energized simultaneously with the other lamps respectively and providing a convenient indication for an operator calibrating the instrument.

11. In apparatus of the character disclosed for use on aircraft, in combination, gyroscope means including an adjustable zero set autosyn mounted on the aircraft for obtaining a gyroscope signal having a polarity corresponding to th direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and having a magnitude proportional to the amount of said deviation, said gyroscope means including a source of A. C. potential and a source of D. C. potential, pitch indicating apparatus adapted to be detachably connected to said gyroscope means, said pitch indicating apparatus including electronic amplifier means having an input gain control, and differential relay means having a variable resistor control, said indicating apparatus also including three lamps of different colors, said indicating apparatus being so constructed and arranged that, while connected to the gyroscope means, said gyroscope signal is utilized to control the relay means and selectively connect said lamps to said D. C. source in accordance with the amount and direction of deviation of the aircraft from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected between the gyroscope means and the indicating apparatus, said signal simulating means being energized from said source of A. 0. potential and including a selsyn device having a variable coupling ratio to provide a variable calibrating signal, said signal simulating means including switching means for selectively switching said calibrating signal and gyroscope signal into said indicating apparatus, said input gain control and variable resistor control providing for calibrating the indicating apparatus while the signal simulating means is connected thereto, said signal simulating means also including three additional lamps of different colors corresponding respectively to the colors of the lamps in said indicating apparatus, said additional three lamps being energized simultaneously with the other lamps respectively and providing a convenient indication for an operator calibrating the instrument.

12. In apparatus of the character disclosed for use on aircraft, in combination, yroscope means including an adjustable zero set autosyn mounted on the aircraft for obtaining a gyroscope signal having a polarity corresponding to the direction of deviation of the instant pitch angle of the aircraft from a preselected pitch angle, and having a magnitude proportional to the amount of said deviation, said gyroscope means including a source of A. C. potential and a source of D. C. potential, pitch indicating apparatus adapted to be detachably'connected to said gyroscope means, said pitch indicating apparatus including electronic amplifier means having a pair of balanced amplifier tubes and having an input gain control, and differential relay means having a variable resistor control, said indicating apparatus also including three lamps of different colors, said indicating apparatus being so constructed and arranged that, while connected to the gyroscope means, said gyroscope signal is utilized to control the relay means and selectively connect said lamp to said D. C. source in accordance with the amount and direction of deviation of the aircraft from said preselected pitch angle, and detachable signal simulating means adapted to be interconnected between the gyroscope means and the indicating apparatus, said signal simulating means being energized from said source of A. C. potential and including a selsyn device having a variable coupling ratio to provide a variable calibrating signal, said signal simulating means including switching means for selectively switching said calibrating signal and gyroscope signal into said indicating apparatus, said signal simulating means including meter means for measuring the currents in the anode circuits of said two tubes, said input gain control and variable resistor control providing for calibrating the indicating apparatus while the signal simulating means is connected thereto, said signal simulating means including three additional lamps of different colors corresponding respectively to the colors of the lamps in said indicating apparatus, said additional three lamps being energized simultaneously with the other lamps respectively and providing a convenient indication for an operator calibrating the instrument.

ARCHIBALD JOHN MCEWAN.

No references cited. 

